TextMagic Messenger lets you send and receive text messages from your computer. It supports sending of messages to large groups, messages of up to 459 characters, a built-in phone book, and the ability to set your own mobile number or a company name as the sender ID. Replies are forwarded to your email address or TextMagic Messenger inbox.
Ozeki NG SMS Gateway sends and receives SMS, MMS, email, and voice messages via GSM modem connections or directly over the Internet (SMPP, UCP, CIMD2) to/from mobile phones. It is useful for SMS services like SMS notifications, two-way SMS systems, automated SMS services, SMS paging, SMS games, billing systems, email-to-SMS forwarding, premium rated SMS services, etc. It supports various APIs.